1. Field of the Invention
The present invention relates to a compressor control device for a car air conditioner in order to discharge liquid refrigerant from the compressor.
2. Description of Related Art
When a vehicle is parked outdoors in the daytime, temperature in the passenger compartment is heated by the sun shine and becomes higher than temperature in the engine room in the day time. If a vehicle is parked for long time, more than 2 days for instance, without using a car air conditioner, the above-mentioned temperature difference occurs repeatedly, resulting in that the refrigerant in an evaporator which is disposed adjacent to the passenger compartment moves to a compressor which is disposed in the engine compartment at a portion lower than the evaporator and a condenser of the air conditioner system and become liquid when temperature falls. When the compressor is operated in this state, the liquid compressed to generate noise and to cause damage to the compressor.
In order to solve the above problem, a compressor control device is proposed in U.S. Pat. No. 5,347,824, which corresponds to Japanese Patent Laid Open Hei 345513. When the air conditioner is started, the device drives the compressor intermittently so that the liquid refrigerant may be discharged from the compressor gradually, thereby to reduce noise caused by compression of the liquid refrigerant.
However, since the above device drives the compressor with the liquid refrigerant therein intermittently, the noise cannot be reduced sufficiently.